A drive used in hybrid vehicles usually consists of a combination of an internal combustion engine with an electric machine. For example, DE 199 62 507 discloses an electric machine situated between an internal combustion engine and a transmission. The rotor of the electric machine is attached directly to the crankshaft of the internal combustion engine, as a result of which it only needs to be mounted on bearings on the transmission sides of the rotor. This approach saves space since there is no need for bearings on the internal combustion engine side.
Synchronous machines with permanent magnets are often employed as the electric machine. Contact between the rotor and the stator is to be avoided since contact between the rotor and the stator can destroy the synchronous machine owing to the high magnetic forces.
When synchronous machines are used and also when, as described in DE 199 62 507, the rotor of the electric machine is equipped only with one set of bearings of its own and is directly connected to the crankshaft of the internal combustion engine, disadvantageous situations arise when the rotor is not connected to the crankshaft, for instance, prior to the assembly, especially before the rotor is connected to the crankshaft, or else when repairs have to be made that involve disconnecting the rotor from the internal combustion engine. When the electric machine or the rotor of the electric machine is not connected to the crankshaft of the internal combustion engine, the rotor can tilt around the bearings on the transmission side, causing contact between the metal and/or magnetic components of the rotor and of the stator of the electric machine, which would destroy the electric machine.